What if you delete a file you later realize you needed or you make a change that doesn't turn out so good but you're many commits down the road from the horror of these changes???
To see how to resolve this I created three text files and initialized git on the directory.
The files initially look like this...
file1.txt
I am file 1
file2.txt
I am file 2
file3.txt
I am file 3
then after these commits...
commit e5bfac1d4f1490de9a4ec8677571257502c1fa51
added a log file and gitignore
commit df80e8d21548e0e68e25c209306e6388e43ab656
another good change to file2
commit 36caed3792a1b3e65b6d767233330d43e6771d17
a good change to file 3
commit d9d54c03bb9b0f75333e248d2a2dbd47e9ab9d5e
a good change to file1 and a bad change to file2
commit 27abe8e3f7e8b1a13c95bf549f641e8ac3fd1191
initial commit
The files look like this...
file1.txt
I am file 1
a good change to file1
file2.txt
I am file 2
a bad change to file2
another good change to file2
file3.txt
I am file 3
a good change to file3
so far so good(?) but now the fun starts, I decide to delete file1 and then commit that...
commit b07c2658149dd4d3ad59cf08728530e6e52e92be
I just removed file1!!
and then I go on my merry way with another change to file3 so now my commit history looks like this...
commit 95b2606921f11884877e0e2d9f5177b2067fd1ee
Another good change to file3
commit b07c2658149dd4d3ad59cf08728530e6e52e92be
I just removed file1!!
commit e5bfac1d4f1490de9a4ec8677571257502c1fa51
added a log file and gitignore
commit df80e8d21548e0e68e25c209306e6388e43ab656
another good change to file2
commit 36caed3792a1b3e65b6d767233330d43e6771d17
a good change to file 3
commit d9d54c03bb9b0f75333e248d2a2dbd47e9ab9d5e
a good change to file1 and a bad change to file2
commit 27abe8e3f7e8b1a13c95bf549f641e8ac3fd1191
initial commit
Now my directory look like this, NOTE: file1.txt is missing in action and...
drwxr-xr-x 7 jrdissermac staff 224 May 22 10:28 .
drwxr-xr-x 7 jrdissermac staff 224 May 22 09:20 ..
drwxr-xr-x 12 jrdissermac staff 384 May 22 10:35 .git
-rw-r--r-- 1 jrdissermac staff 4 May 22 10:04 .gitignore
-rw-r--r-- 1 jrdissermac staff 64 May 22 10:02 file2.txt
-rw-r--r-- 1 jrdissermac staff 64 May 22 10:34 file3.txt
-rw-r--r-- 1 jrdissermac staff 2389 May 22 10:37 log
File2.txt has a bad change...
file2.txt
I am file 2
a bad change to file2
another good change to file2
file3.txt
I am file 3
a good change to file3
another good change to file3
And at this point I decide to push this mess up to github making a public copy of the repo, and complicating matters...
git remote add origin https://github.com/jdisser/gitHackery.git
git push -u origin master
file3.txt
I am file 3
a good change to file3
another good change to file3
yet another good change to file3.txt
So now the problem is that I need to get file1.txt back and get rid of that bad change in file2.txt ON GITHUB!!! So this limits what can be done with git reset since this happens in the local repo and if you try to push it git complains that there are missing commits.
But all is not lost. You CAN use git checkout on a single file instead of a whole repo. You have to checkout the commit before the deletion and then make a commit to restore it like this...
NOTE: you can use just a portion of the commit number about 7 characters works
git checkout e5bfac1d4 file1.txt
git add -A
git commit -m "restore file1.txt using git checkout TheCommitNumber TheFileName.whatever"
git push origin master
And to remove that "bad" change to file2 that was done long, long ago we can use revert on just the commit that made the bad change. Revert creates an offsetting change to the repo contents that will not break the chain of commits in the public repo on github. So first lets see what commit we want to revert with a git log...
commit 0c9db28bab6c8fcc71cc5ecd37be88bba87be588
restore file1.txt using git checkout TheCommitNumber TheFileName.whatever
commit 39870484853a8d0c8382dbb0aef313600165fcd2
yet another good change to file3
commit 95b2606921f11884877e0e2d9f5177b2067fd1ee
Another good change to file3
commit b07c2658149dd4d3ad59cf08728530e6e52e92be
I just removed file1gaa
commit e5bfac1d4f1490de9a4ec8677571257502c1fa51
added a log file and gitignore
commit df80e8d21548e0e68e25c209306e6388e43ab656
another good change to file2
commit 36caed3792a1b3e65b6d767233330d43e6771d17
a good change to file 3
commit d9d54c03bb9b0f75333e248d2a2dbd47e9ab9d5e
a good change to file1 and a bad change to file2
commit 27abe8e3f7e8b1a13c95bf549f641e8ac3fd1191
initial commit
The offending commit is d9d54c03b where a good change was made to file1 and the bad one to file2. Reverting this commit will remove both of them but we can still get this to work using the sorcery of git! First we'll continue with the idea of reverting that offending commit thusly...
git revert d9d54c03b
Yikes! I get this message...
error: could not revert d9d54c0... a good change to file1 and a bad change to file2
hint: after resolving the conflicts, mark the corrected paths
hint: with 'git add <paths>' or 'git rm <paths>'
hint: and commit the result with 'git commit'
Which is very helpful thanks to our friends at Git! So looking at file2.txt now we see
file2.txt
I am file 2
<<<<<<< HEAD
a bad change to file2
another good change to file2
=======
>>>>>>> parent of d9d54c0... a good change to file1 and a bad change to file2
so we need to edit file2.txt and then do a git add file2.txt to put it in the working tree. After we do that our files look like this...
file1.txt
I am file 1
file2.txt
I am file 2
another good change to file2
file3.txt
I am file 3
a good change to file3
another good change to file3
yet another good change to file3.txt
But we're now missing the good change to file1.txt! It got reverted along with file2.txt! But all is not lost, it's not gone in the sense it doesn't exist since we can go back in time with our new friend
git checkout <commit> <filename>
and after we do this...
git checkout 36caed37 file1.txt
our files look like this...
file1.txt
I am file 1
a good change to file1
file2.txt
I am file 2
another good change to file2
file3.txt
I am file 3
a good change to file3
another good change to file3
yet another good change to file3.txt
And all is again right with the world....
EPILOG
Unless you made a change in .gitignore! which will add unwanted files in the repo! But removing stuff is way easier than restoring it!
Here's the whole git log for those of you scoring along at home, please mark your scorecards accordingly!
commit c598890e08242714b949cf4e4e67d1b9ccf853f9
now restore file1.txt back to a good state using git checkout 36caed37 file1.txt
commit 7bef7c911463ca14fd98da059a4ef1d6585d4328
use git revert d9d54c03b to revert the bad change to file2
commit 0c9db28bab6c8fcc71cc5ecd37be88bba87be588
restore file1.txt using git checkout TheCommitNumber TheFileName.whatever
commit 39870484853a8d0c8382dbb0aef313600165fcd2
yet another good change to file3
commit 95b2606921f11884877e0e2d9f5177b2067fd1ee
Another good change to file3
commit b07c2658149dd4d3ad59cf08728530e6e52e92be
I just removed file1gaa
commit e5bfac1d4f1490de9a4ec8677571257502c1fa51
added a log file and gitignore
commit df80e8d21548e0e68e25c209306e6388e43ab656
another good change to file2
commit 36caed3792a1b3e65b6d767233330d43e6771d17
a good change to file 3
commit d9d54c03bb9b0f75333e248d2a2dbd47e9ab9d5e
a good change to file1 and a bad change to file2
commit 27abe8e3f7e8b1a13c95bf549f641e8ac3fd1191
initial commit